This is a sealed class, so you can not inherit from it. Also, the constructor is private, so you cannot create a new instance of it. An ImageListStreamer is returned by the ImageStream property of the ImageList. However, you cannot use this class to load images to an ImageList control by directly assigning the ImageStream property from one ImageList. Instead you should directly assign one ImageList instance to another (for example, ImageList2 = ImageList1).